Anisotropic microstructured poly(vinyl alcohol) tissue-mimicking phantoms [Letters]

Novel microstructured PVA phantoms mimicking fibrous tissues have been developed using a simple freeze-casting process. Scanning electron micrographs reveal highly anisotropic microstructure with dimensions of the order of 5 to 100 μm. Characterization of an example phantom revealed acoustic properties consistent with those found in fibrous tissues. At 20 MHz, the velocity measured parallel to the microstructure orientation of 1555 ms^-1 was significantly greater than that perpendicular to the microstructure of 1537 ms^-1. The attenuation coefficient was measured to be 5 dB·mm^-1 and proportional to the 1.6 power of frequency, which is in good agreement with that for normal human myocardium.